CHRYSOBERYL and ALEXANDRITE from the PEGMATITE DISTRICTS of MINAS GERAIS, BRAZIL by Keith Proctor

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CHRYSOBERYL AND ALEXANDRITE FROM THE PEGMATITE DISTRICTS OF MINAS GERAIS, BRAZIL By Keith Proctor

This fourth article in the author's series he two commercially most important gem varieties of on the pegmatite districts of Minas Tchrysoberyl-cat's-eye chrysoberyl and alexandrite- Gerriis, Bmzil, focuses on chrysoberyl, are among the world's rarest gemstones (figure 1).The state particr~larlythe rare but coveted varieties of Minas Gerais, Brazil, and the island of Sri Lanlza are cat's-eye and alexandrile. Most of the presently the world's two largest suppliers of chrysoberyl, catk-eye chrysoberyls on the genl rnrrrlzet cat's-eye chrysoberyl, and alexandrite, although Russia today conle fron~Brazil, primarily from the region around lhe Americana and historically has produced some fine material. Since pro- Sontana valleys. This article examines duction from Sri Lanka has dropped off dramatically in some of the more important mines in this recent years and the classic Uralian deposits are most region, with a detailed description of the likely exhausted, the major future production will proba- Barro Preto deposit. Flirther south, the bly come from Brazil. Molacacheta area has produced a number Chrysoberyl, with a hardness of 8'12, is the third of fine alexandrites during the last 13 hardest of the gemstones, following only diamond and years. Since October 1986, however, it has corundum. Known in antiquity but not properly identi- been overshadowed in both quality and fied, chrysoberyl was found mixed with tourmaline and quantity by [he small Lavra de Hematita, other gems in the gem gravels of Ceylon by at least the late which produced 50 kg of fine alexandrite 1600s. In Ceylon, the Singhalese natives considered chrys- in less than three monlhs. Tliese two oc- oberyl a superior kind of tourmaline (Ball, 1930).The name currences are also described in detuil. (chryso-, from Greek for yellow or golden, plus beryl) indicates that other, more sophisticated investigators considered chrysoberyl to be a variety of beryl (Sinlzankas, 1964). It was finally chemically identified as a distinct species by Werner in 1789, and chrysoberyl with the chatoyant, or "cat's-eye" effect, was dubbed "cymophane" ABOUT THE AUTHOR by Hauy in 1798 (Bauer, 1904; Bank, 1973). Keith Proctor is president 01 Keilh Proctor Pre- Brazil was recognized early on as a major source, with cious Gems, a wholesale import lirm in Colorado Springs, CO. the first mining exports (probably from the Araquai and Minas Novas districts)occurring by 1805. A huge-almost Acknowledgments: Special thanks to H. Kennedy, A. Tavares, and Dr. R. Nash, without whose help 8 kg-chrysoberyl was listed as one of the treasures of Rio this article would not exist. The input 01 /he lollow- de Janeiro in 1828 (Bauer, 1904; Ball, 1930).Brazilians have ing is greatly appreciated: K. Elawa~W Brennan, long coveted chrysoberyl, which they called "cris6lita," S. Domingos, Dr. H. Bank, Ds K. Schrnetzer, Dr. F. Pough, Dr. E. Gijbelin, S. Watt, C. Bank, Dr. J. and even named the city of Cris6lita (probably another Raggi, Dc D. Schwartz, J Drey and 0 Neto. early source) after the gem. Today, Minas Gerais is the Thanks also go to L. Mollett lor typing /he rnanu- major source of chrysoberyl in Brazil. The Brazilian scr~pt,to L. Rayburn lor lranslations, and especially to Mauna Proctor lor her help in translating, chrysoberyls range in color from yellow to yellowish typing, and edit~ngand lor her constant support. green, olive green, gold, brown, and, rarely, "ruby" red 0 1988 Gemological Institute 01 America (figure 2).

16 Chrysoberyl and Alexandrite of Minas Gerais GEMS & GEMOLOGY Spring 1988 Figure I. Minas Gerais is a major source of fine crrt's-eye chrysoberyl and alexandrite. The "honeyu-colored cat's-eye chrysoberyl shown here (5.47 ct) is from the Amer~cano/Saninnaval- ley region; the alexandrite (3.03 ct), which appears red in incandescent light (here) and bluish green in fluorescent light, is from the newest deposit, Lavra de Hematita. Rings courtesy of Silverhorn, Santa Bar- bara, CA; photo O Tino Hammid.

The color-change variety of chrysoberyl, alex- In the almost 200 years since chrysoberyl was andrite, was discovered in the Ural Mountains of first mined in Brazil, many tens of thousands of Russia in 1830; it was named after the heir- carats of chrysoberyl, cat's-eye chrysoberyl, and apparent to the Russian throne, the future Alex- alexandrite have been talzen from deposits in ander 11. The best Russian stones tend to be bluish northeast Minas Gerais and the states of Bahia and green in daylight (or fluorescent light) and pinlz, Espirito Santo. At least 95% of the chrysoberyl and reddish purple (raspberry),or, rarely, "ruby" red in cat's-eye chrysoberyl found in Minas Gerais in incandescent light (Pough, 1976). Most of the recent years has come from the many deposits in Brazilian alexandrites discovered before October the Santana and Americana valleys, near the city of 1986 are also green in daylight but are more Padre Paraiso in the Te6filo Otoni-Marambaia amethystine or pinlz in incandescent light (Kunz, pegmatite districts (K. Elawar, H. Kennedy, A. 1913j Pough, 1973). However, the best gems from Tavares, pers. comm., 1987; figure 4). The Barro the newly discovered Lavra de Hematita (also Preto and Gil claims, as well as the Faisca and lznown as Nova Era or Itabira) alexandrite deposit Cilindro deposits, are particularly notable. Vir- are predominantly bluish green to greenish blue tually all of the finest alexandrite produced in the (called pavio in Brazil) in daylight and pinlz, last 13 years has been mined from the pegmatite raspberry, "rhodolite," or "ruby" red in incandes- regions associated with the cities of Malacacheta cent light (figure 3). The rarest of the rare alex- and Itabira. In these two areas, the Corrego do Fogo andrites is fine cat's-eye alexandrite. and Hematita deposits are major producers for the

Chrysoberyl and Alexandrite of Minas Gerais GEMS & GEMOLOGY Spring 1988 17 found in the Americana valley. The earliest report is of a 10-ctgem that was cut in 1932; a notable find also occurred in 1975 (H.Bank, pers. comm., 1984). The Santana valley has produced only a few pale alexandrites with poor color change from near the junction of the Barro Preto and Gil creeks (H. Kennedy, pers. comm., 1987). The following discussion provides what little information is available on the Faisca and Cilindro mines, in the Americana valley, and a detailed description of the mining operation at Barro Preto (with reference to the nearby operation at Gil), in the Santana valley.

Location and Access. These two valleys lie east of and roughly parallel to highway BR- 116 (figure 4). The western valley is the watershed for the San- tana liiver, which runs directly south from near Padre Paraiso; the parallel eastern valley is the watershed for the Americana River. The two valleys are separated by a ridge of hills, which is probably the original source of the chrysoberyls. Numerous streams that flow into these two rivers Figure 2. This 41 -ct twinned crystal, found nt cut smaller valleys along both sides of this range of Malacacheta in 1976, is a rare example of red hills. It is within these smaller valleys that the chrysoberyl. Courtesy of Henry IZennedy, Ted- chrysoberyls are found. filo Otoni, Brazil; photo O Fred L. Elsnau. These chrysoberyl-bearing valleys may be reached by traveling north from Teofilo Otoni on world market. These deposits and the gems they BR-116 to lzm marker #175 (indicating the dis- produce are described below. tance remaining to the Bahia border], 5 km north- The reader is referred to part 1 of this series east of Padre Paraiso. To reach the Gil and Barro (Proctor, 1984) for a detailed description of the Preto claims, one then takes a good dirt road east pegmatite deposits of Minas Gerais, the terminol- almost 10 lzm, toward the city of Aguas Formosas. ogy used to describe these gem deposits, and the Just before reaching the hamlet of Ribeirao de various mining methods used. To the author's Santana, talze the road south into the Santana lznowledge, the various types of chrysoberyl are valley approximately 7 km to reach the Gil and not being subjected to any form of color or phe- Barro Preto creeks. To reach the Faisca and Cil- nomenon enhancement. indro garimpos (or workings, used to refer to a specific series of pits in the alluvium), instead of CHRYSOBERYL FROM THE turning south at the 10 Izm junction one continues AMERICANA AND SANTANA VALLEYS for an additional 18 lzm east and then turns south As early as 1846, chrysoberyl was reported from on another dirt road to the mining area, which lies C6rrego de Santa Anna (probably the Santana along the Faisca and Topizio streams, two tribu- valley), east of Araquai, by Van Helm Reischen. taries of the Americana River. The earliest record of cat's-eye chrysoberyl in this region comes from Dr. Hermann Bank, whose The Faisca and Cilindro Mines. Since 1939, Rudolf father observed them when he visited the Ameri- Ziemer and his family have mined relatively large cana valley on horseback in 1910. Not knowing quantities of chrysoberyl and cat's-eye chrys- what they were, the local cattle ranchers had been oberyl, and minor amounts of alexandrite as well throwing the gems away (H. Bank, pers. comm., as some topaz, from the Faisca mine (also known as 1988). the Ziemer mine) in the Americana valley. In rare instances, fine alexandrites have been Ziemer's son (also named Rudolf) mechanized

18 Chrysoberyl and Alexandrite of Minas Gerais GEMS & GEMOLOGY Spring 1988 their mining operation about 1975, resulting in a dramatic increase in production from what is probably the largest chrysoberyl operation in Bra- zil at the present time (A. Tavares, pers. comm., 1988). The Faisca mine lies directly over the mountain range that is opposite the Gil and Barro Preto concessions. Owned by Hilton (Zequinha) Lopes, the Cil- indro mine is adjacent to the Faisca mine. After the Faisca and the combined Gil and Barro Preto operations, it is probably the third largest producer in the area. Unfortunately, no production statistics are available for either the Faisca or the Cilindro mine. See figure 4 for additional significant workings in this area.

The Gil and Barro Preto Concessions. In 1960, a 785-gram crystal of gem-quality cat's-eye chrysoberyl was found in the GilIBarro Preto region. In February of that year, Agenor Tavares obtained the crystal and, in 1967, acquired the mineral rights to these properties as a concession. He initiated a period of greater activity that resulted in the production,oi more than 500 grams of gem-quality chrysoberyl; and cat's-eye chrysoberyl between 1968 and 1973 (theratio of chrysoberyl to cat's-eye chrysoberyl, found is roughly 4 to 1). However, Figtrre 3. The finesr alexandrites from rhe newly relatively little came out in the course of the next discovered Hematzta mine range froin bright five years (A. Tavares, pers. comm., 1987). For two pink to red in incandescent light. These stones (0.95 ct to 2.49 ct) are courtesy of Kreinentz d years, 1979-1 980, a Japanese company worlzed Co., Newark, Nl. Photo 0 Tino Hammid. both Barro Preto and Gil with heavy machinery, but they found less than 6 kg of chrysoberyl and cat's-eye chrysoberyl combined. Currently, Henry colluvial-alluvial gem gravels (cascalhos) which Kennedy is the major lessee. His diggings cover a lie beneath various layers of red soil and gray or little less than a lzilometer in each of the valleys, black clay and/or sands of various colors (R.Nash, although most of his effort has been in Barro Preto. pers. comm., 1986). Accessory minerals found Production has increased steadily since he became include schorl, beryl (heliodor and aquamarine), involved in the early 1980s. Kennedy was instru- topaz, rhodolite garnet, andalusite, considerable mental in providing the geologic, mining, and quartz, and olivine (H. Kennedy, pers. comm., production information given below. Also of great 1986). help was Dr. Rex Nash, a geologist in Minas Gerais In the Gil valley, most of the rough gem who has studied the area extensively. material is small and well rounded, which sug- gests that it was transported some distance from Geology and Occnrrence. The Gil and Barro Preto the original source. At Barro Preto, however, many claims are at an elevation of approximately 750 m. of the rough brolzen pieces have terminated faces These "highlands" are basically granite and grani- or sharp brolzen edges, which indicates that this tic gneiss with innumerable pegmatite intrusions. area is probably closer to the original host rock. For Because of the number of pegmatites in this the most part, the following geologic discussion is region and their highly decomposed state, the limited to the higher of the two valleys, Barro secondary deposits are rich in gem minerals. The Preto, which has produced more large gems. Gil and Barro Preto valleys are typical of the region There are seven recognizable layers (which in that most of the chrysoberyls are found in vary in thiclzness throughout the area) in most

Chrysoberyl and Alexandrite of Minas Gerais GEMS & GEMOLOGY Spring 1988 19 parts of Barro Preto (H. Kennedy, pers, comm., 5 cm (at which point it contains no gems] to 1 m 1988): thiclz. A thiclzer layer with good-sized quartz 1. A red lateritic soil overburden. gravel is a strong indicator that gem material is 2. An organically rich layer of blaclz clay mixed present. Approximately 15-20% of the gem withsand that is up to 1.25 m(4ft.)thiclz (found chrysoberyls produced at Barro Preto, inore only occasionally in the Gil valley; burro preto than 90% of which have sharp brolzen edges or means blaclz clay]. crystal faces, are found in this layer. This 3. An upper cusculho layer of gem pebbles mixed appears to be a colluvial layer that has weath- with sand and rounded roclzs that lies above the ered out of a nearby source and been eroded into present creek level. This gravel layer is reddish this narrow valley (see Proctor, 1984, for a brown from iron-oxide staining, and varies from discussioil of colluvial/alluvial deposits].

Agure 4. The Americana and Santana valleys have produced approximately 95% of the chrysoberyl and cat's-eye chrysoberyl found in Minas Gerais during the last 50 years. The major deposits are identified. See the first article in this series (l'roctor, 1984) for o mop of all the mnjor gem pegmatite mines in northeastern Minas Gerais. Artworli by Ian Newell.

20 Chrysoberyl and Alexandrite of Minas Gerais GEMS & GEMOLOGY Spring 1988 Figure 5. Water is an on- going problem at Barro Prelo. Periodically during the da)s the miners must pump the water out in order to gain access to the gem- bearing gravels. llhoto by Henry Kennedy

4. A black clay (similar to layer no. 2) that contains iron oxides, and must be brolzen up with long so much organic matter that, when dried out, it steel bars. will actually burn like peat. Local geologists In contrast to the upper, colluvial, gem-bearing suggest that this layer, which blankets the layer, the bottom.cascalho is between 0.5 to 1 m entire valley, resulted from the destruction of a thick and is usually found in the river bottom. As great &,ih forest. The roots of this forest held before, the thicker the layer is, the greater its gem back erdsion of the surroundiilg hills; when the potential. In some areas, the chrysoberyls found in forest was destroyed, erosion accelerated rap- this layer are well worn, a truly alluvial deposit. As idly thds laying down the upper cascalho layer. mining activity moves northwest toward the gran- 5. A gray clay layer from 10 to 20 cm (4-8 in.) thick ite hill, there is a greater concentration of gem that is sometimes extremely hard and is be- chrysoberyls and those recovered show fewer signs lieved to be the product of sedimentation in of alluvial wear, with complete terminations on ancient lalzes, ponds, or streams. some specimens; this material has not moved far 6. A fine sand layer of different colors-yellow or from its original source. Approximately 80-85% red when iron oxide-rich; white if the iron of the gem production at Barro Preto comes from oxide has been leached out - that usually grades this layer. into coarser sands as one goes deeper. The altered, decomposed "spongy" gneiss bed- 7. A lower cascalho layer in which the gems are rock lies directly under the last cascalho layer, and mixed with coarse, rounded, mostly granite loolzs like thiclz, hard clay, as it does at Marambaia river roclzs with perhaps only 10-20% quartz and Tres Barras. The latter deposits, however, each gravels and some sand (unlike that at the have only one gem-bearing layer. Marambaia and Tres Barras deposits-see Proc- Because the area is so highly weathered, it is tor, 1984-which is 99% quartz pebbles). difficult to determine whether the chrysoberyl The color of this cascalho layer varies from formed within a pegmatite or in the host rock into white, rose, brown, or orange to gray; it is which the pegrnatites were intruded. However, frequently "braided," with intertwining strands some gem-quality chrysoberyl has been found in of different colored gravels, each of which prob- situ in a nearby pegmatite at the Simso mine (H. ably represents a different creek and different Kennedy, pers. comm., 1988). time period. The most productive gem-bearing gravel "braids" are pink and brown; the least Mining. Hundreds of pits have been dug in these productive are white. Tremendous effort is valleys in recent years, but there is a constant expended in searching for this linha mestra problem with water; until pumps were used con- (master gravel). The gravels are cemented into sistently, little mining progress could be made hard masses by a combination of a silica and (figure 5). To find the bottom cascalho layer,

Chrysoberyl and Alexandrite of Minas Gerais GEMS & GEMOLOGY Spring 1988 21 Figure 6. Here a backhoe is used to remove the red soil overbiirden nnd the first layer of Olnck clay n~ixedwith snnd to get to the top cascalho layer (the yellowish n~aterinlin front of the Oaclthoe) at Barro Preto. Water is o threat to mechanized mining as well; note the prinlp on the lefi. The grnnite insel- berg behind the operatioil niciy hnve been the original source of the chrysoberyl. Photo by Henry IZennedy

Fig~ire7. Large granite bo~ildersoften block ac- "modern" garimyeiros (independent miners) dig cess to the top gem-benring layer at Barro Preto square pits down through the layers in the valley and must be blasted into smoller pieces for re- floor, stake the walls with wood to prevent cave- moval. Here the hole hns nlreody been drilled ins, and then pump the water out periodically so and the dyi~amite(note the sticks in back) they can work the gem gravels. Kennedy also with fuse has been put in place. The miner puts reroutes the stream during the dry season and then newspaper on top of the dynami~eto protect the chnrge and then pncks it with soil so that excavates. Some miners give up the search for the t11e rock will break uniformly Photo by Henry lower layer altogether and just work the upper Kennedy layer with a back-hoe; even then, water pumps are usually required (figure 6). Another obstacle is big granite boulders, which often lie above and even iiltermixed with the gem gravels. These have to be pried loose or dynamited so they can be hauled away (figure 7). During the course of one six-weel< project, Ken- nedy and his men tediously bored two-foot-deep holes, one after another, into each of literally hundreds of large granite boulders (73 in one day alone) to gain access to a very thick layer of cascalho. They were devastated to find only one very poor cat's-eye in the tons of gem gravel that they extracted. Once it is removed, the cascalho must bc washed and sorted. Kennedy uses a system he devised of four screens, one on top of the other,

GEMS & GEMOLOGY Spring 1988 with about 15-25 cm (6-10 in.) separating them (figure 8). From the top down, each screen has a smaller mesh, and since the chrysoberyl pebbles are generally small, most eventually end up on the bottom screen. When the upper "box" is loaded with cascalho, a water cannon is used to separate the gems and clean the gravel. The sands and clays fall through to the ground, and the remaining gravels in each size group are hand sorted for the gem rough.

Production. The Gil valley produces many more gemstones than Barro Preto produces, but Barro Preto yields much bigger pieces of rough. Accord- ing to Kennedy (pers. comm., 1988))the 40 garimpeiros who work this region consistently produced (as of 1985) 100 grams of good rough in an average week. For most of 1986 and 1987, however, production dropped to 10 grams per week because many of the garimpeiros moved to the Hematita alex- Figure 8. To sort the gem gravels qriickly und andrite deposit. In January 1988, however, Ken- efficiently at Barro Preto, the miner uses a wu- nedy and a small crew removed 300 grams of ter cannon to force them through four screens chrysoberyl rough from two small pits in Barro of different mesh. Photo by Henry Kennedy Preto. Sipce 1960, these two valleys have produced only 12-1f5 kg of fine gem chrysoberyl. Only 30 to 40 ct of clean stones result from I00 grams of Figrrre 9. This 11.5-ct stone from Barro Preto chrysoberyl rough, and only approximately 20% of shows the sharp, well-centered eye on a these stoiles are the far more valuable cat's-eye. "honeyn-colored body that is so valrred in fine With all of this activity, however, the area is still cat's-eye chrysoberyl. The cat's-eye phenomenon comparatively untouched; both Kennedy and the is caused by the presence of muny relutively concession holder, Tavares, predict several decades short needles that are oriented parallel to the of low productivity and estimate that only 30% of c-axis of the original crystal (Webster, 1983). the AmericanaISantana valley area has been de- Stone courtesy of Henry Kennedy; photo O pleted. Tinn Unmniirl The chrysoberyl and cat's-eye chrysoberyl found at Barro Preto is similar in color to that found elsewhere in Brazil, ranging from pale yellow through yellowish green and "honey" to greenish brown and even dark brown (thelast, at times, with a blue "eye"); rarely, there are even some bicolors (yellow and dark brown). Most of the material is yellowish green to "honey" (figure 9). The cut cat's-eye chrysoberyls average 5 ct in weight; the nonphenomenal chrysoberyls are usually clean but small, seldom cutting stones larger than 2 ct. While the rough Kennedy has mined ranges up to 10 grams, he has seen a 63-gram piece of gem-quality cat's-eye chrysoberyl from the Gill Barro Preto region. The largest cut chrysoberyl the author knows of, which was probably mined from these valleys, is a 114-ct cushion cut that is now at the Smithsoilian Institution (Desautels, 1979).

Chrysoberyl and Alexandrite of Minas Gerais ALEXANDRITE FROM THE Location and Access. The Malacacheta region is 20 MALACACHETA REGION lzm directly north of Malacacheta City in the More than 100 (air)lzm southwest of Barro Preto watershed of the Settibal and Soturno rivers (figure lies what for 13 years was one of the few regions in 10).Diggings extend about 8 lzm along both sides of the world that produced fine alexandrite - Mal- Fogo Creelz, along 20 lzm of the Soturno River, and acacheta (also known as Corrego do Fogo or just along a few kilometers of the Setubal River. Minor Fogo). Until the recent discovery at the Lavra de deposits have also been found in a small section of Hematita (discussed below), it was Brazil's fore- the Setubinha River. The valley regions can be most producer of this rare gem material. reached from the city of Malacacheta by taking a (sometimes impassable) dirt road due north or, more easily, from Setubinha City by talzing a dirt Figure 10. For 13 years, the Malacacheta region road due east to the village of Palmeiras and then produced some of the finest alexandrite in Bra- south on another dirt road into the valleys. zil. The greatest mining activity was along 8 km of both sides of ihe Cdrrego do Fogo, along History. One evening in 1975, Joiio Rodrigues and 20 ltm of the Soturno River, and along a few lti- his sons set up camp along the Fogo Creelz. As the lometers of the Setubal and Setubinha rivers. sons carried mud from the creek to encase the See the inset map in figure 4 for the location of mandioca roots being prepared for the evening Malacocheta in relation to the other mining meal, a native fubd, they found nodules of what areas discussed in this article. Artwork they thought were green tourmaline. When these by Ian Newell. were later identified as fine alexandrite, garimpeiros from all over rushed to the region (H. Kennedy, pers. comm., 1987). Over the course of the next 13 years, the search for the rare but very valuable pieces of rough would lead to robberies, claim jumpings, and even several killings. During the period of peak production, 1980-1982, approximately 4,000 to 5,000 miners worked these valleys. At first, they found relatively productive alluvial deposits along a 150- to 300-m- wide swath down the Fogo valley encompassing both sides of the creek. The garimpeiros dug the typical square pits to reach the gem-bearing cascalho layer and then shoveled the gravels onto the pit bank. After allowing the pit to fill with water- which required about the same time as eating lunch and having a cigarette- the miners waded into the water and used circular screens (called peneirns) to wash the gravels (H. Kennedy, pers. comm., 1987; see Proctor, 1985a, figures 14 and 15, for a similar process).

Geology and Occurrence. All of the alexandrite found to date has been purely alluvial with no in- situ occurrences to determine the nature of the original host rock. At the Itabira emerald deposit in Minas Gerais, as at the Goiss and Carnaiba emerald deposits, small amounts of alexandrite have been found in a metamorphic mica-schist with the emeralds. This is also the environment in which alexandrites have been found at the Tak- owaja River, USSR; Umba River, Tanzania; Fort

24 Chrysoberyl and Alexandrite of Minas Gerais GEMS & GEMOLOGY Spring 1988 Victoria, Zimbabwe; and at the Transvaal in South Africa (Pough, 1976). There are, however, numerous pegmatites in the Malacacheta region. Further study is needed to determine the exact origin of these deposits.

Production. Since 1975, all of the mining activity has produced only about 2 lzg of very good, mostly clean rough and approximately 6-8 kg of lesser quality material. Most of this production was alexandrite; very few pieces of "honey"-colored chrysoberyl and cat's-eye chrysoberyl were recovered. The author knows of alexandrite rough as large as 18 grams; the finest faceted stones include a 13 ct and a 15.6 ct. A 14.6-grampiece found in the Soturno River in 1985 yielded a superb 18.5-ct cat's-eye alexandrite, one of the world's largest (figure 11). In addition, also in 1985, an 8.1-gram twinned crystal of very rare dark red chrysoberyl (withno color change) was recovered at Corrego do Fogo (again, see figure 2). Limited amounts of very fine, but small (2-3 ct] blue sapphires have been found in these valleys along with some, also small (23ct),gcm peridot as well as 50-70 kg of good Figure 11. One of the rarest stones to emerge rubellite ;crystals. from the Malacacheta region is this 18.5-ct Overall, the alexandrites from Malacacheta cat's-eye alexandriie. Courtesy of Henry Ken- are much smaller than those from the Hematita nedy; photo O Harold eS Erica Van IJelt. deposit discussed below, because the rough is not as clean or as large. These stones generally are even some 25- and 30-ct clean faceted gems of yellowish green in sunlight and pink in incandes- exquisite beauty that exhibit an extraordinary cent light. The best gems from Malacacheta do not color change. compare with those from Hematita. The author feels that the Malacacheta region Location and Access. The Hematita alexandrite will continue to produce very small quantities of worlzings can be reached from either Governador good alexandrites for many years. The most easily Valadares or Belo Horizonte by talzing main high- accessible and obvious deposits have been exten- way381 to an unnumbered dirt road that is 15 km sively but not completely worked. Currently only southwest of the city of Ant6nio Dias and 5 lzm about 50 garimpeiros are working in this region, northeast of Nova Eraj follow this road (which has not because of a total lack of potentially good a sign labeled Hematita) due north 23 km to the areas, but because Hematita is the new El Dorado. mining area, which is just off the right side of the road and only 34km southwest of the hamlet of ALEXANDRITE FROM THE Hematita (figure 12).The mine is correctly called LAVRA DE HEMATITA DEPOSIT Lavra de Hematita (lavra means mine), but it is Although the Malacacheta region represents one of also lznown internationally as Nova Era; most the world's great alexandrite locations, in 1987, Brazilians refer to it as Lavra de Itabira, or more over a period of less than three months, the size and commonly just Itabira. For the purpose of this quality of production from a new discovery called article (and to avoid confusion with the Itabira Lavra de Hematita dwarfed its importance. Many emerald locality, where alexandrites have also prominent dealers and collectors already acclaim been found), Hematita will be used. this new area as history's greatest alexandrite discovery. To date, Hematita has yielded tens of History. The history of this discovery begins with kilos of alexandrites, including many 10-ct and two 10-year-old boys, one the son of a local farmer

Chrysoberyl and Alexandrite of Minas Gerais GEMS & GEMOLOGY Spring 1988 25 Figure 12. Perhaps the largest deposit of alexandrite ever discovered was found ot the Lavra de Hematita (LH), a small orea just southwest of the small town of Heinatitu in the Itabira mining district. See the inset mup in figure 4 for the location of Itabirn in relation lo the other mining areas discussed in this c~rticle. Artwork by Jon Newell.

named Xisto. The boys often played in two broolzs attempting to dig some of the rough. In November that cut through part of the homestead owned by a 1986, two Brazilian companies headed by Socrates farmer named Policarpo, which is located within a and Xisto almost simultaneously requested an eucalyptus plantation owned by Ferro Brasileira, exploration permit from the government to open an Itabira steel company. (Theeucalyptus trees are the alexandrite occurrence. By December, after burned for charcoal that is used to produce steel.) much squabbling among themselves, the two The boys put together a collection of small rough groups combined their efforts and began mining gems that they had found in the creelzs, and in the area by hand (as yet without the official October 1986 toolz them to the nearby city of Santa government license).They agreed to lzeep the new Maria de Itabira. They sold the stones to a man discovery quiet for fear garimpeiros would invade named Rodazio who, thinking they were an- the property. Although Ferro Brasileira owned dalusite, purchased them for a pittance and told almost all of the land, the mining rights in Minas the boys to come back with more if they could. Gerais belong to the state and any licensed garim- During November, the two boys dug more of the peiro can invade the property and mine at will. stones, selling some and showing others to Poli- Infighting and clandestine digging continued carpo, Xisto, Socrates (whoowns Macil, a hematite until the first big parcel - 21.5 grams - arrived in mining company nearby), and Arthur (another Teofilo Otoni on January 28, 1987, and was shown homesteader living within the plantation); all to A. Tavares, K. Elawar, and other prominent attempted, at first unsuccessfully, to identify the dealers. Each recognized that this was among the stones (A. Tavares, J. Drew, L. Nercessian, pers. finest alexandrite ever seen and sensed the real comm., 1987). importance of the find. On February 8, the first five In the meantime, Rodazio sold his ever-grow- faceted stones (totaling only 11 ct) sold for ing collection of "andalusite" to a visiting Teofilo US$40,000 to Japanese buyers (A. Tavares, pers. Otoni gem dealer, Joaquim Feijio. Feijiio's suspi- comm., 1988).By February 15, several dealers and cions were confirmed when he toolz the rough to garimpeiros had discovered the location of the Teofilo Otoni: This was indeed alexandrite-and deposit. By March 15, the trickle of garimpeiros among the best anyone had seen from Brazil. As he had turned into a flood; by the end of March, 3,000 sought the source, he eventually met Socrates, pit diggers had invaded this very small valley Arthur, Xisto, and Policarpo, who by now were all deposit (see figure 13). A tent city sprang up

26 Chrysoberyl and Alexandrite of Minas Gerais GEMS & GEMOLOGY Spring 1988 Figure 13. M-,,,,in a matier of weeks ofter the Hematitn deposit was discovered by local niiners and dealers, bpth sides of this meandering brook, and even the brook itselk were invaded by thousands of miners. Note in the pit on the riglit the clear demarcation of three layers-an overburden of clay and sand, the heavily quartz- and l

Chrysoberyl and Alexandrite of Minas Gerais GEMS & GEMOLOGY Spring 1988 27 barbed wire fence around the entire mining area, 500 m2 (again, see figure 13).Two small broolzs cut but most of the remaining miners were willing to through this alluvial deposit and meet at the risk everything for a chance to dig. The reader can center of the richest find (S. Domingos, pers. imagine the situation of 60 to 100 military police comm., 1987).This brook divides again and then trying to control thousands of hungry and angry rejoins before leaving the deposit area, at which miners. They became more brazen after dark, and point it passes over a waterfall and empties into the every night many (sometimeshundreds) of miners Corrego do Liberdade (Liberty Creelz), which runs would go through the fences and mine by moon- almost perpendicular to the fall line of the valley light, which resulted in several shootings. Many itself. Significantly, little or no gem alexandrite who were there to maintain control were seen was found below the Corrego do Liberdade, al- digging in the pits themselves. though a baclzhoe operation near this creek did The mine remained "closed" in this fashion yield small amounts of rough. until August 18, when Warren Brennan, a geologist At least four geologists and/or mining engi- and gemstone dealer from Los Angeles, arrived neers have visited this deposit. They have identi- with a group of people, including 10 federal plain- fied three distinct "environments" (and variations clothes police and a judge from Hematita. This thereof; again, see figure 13) containing the gem- group "re-opened the mine," and 150 of the 800 bearing gravel layers. garimpeiros who still remained outside were let in In part of the valley, Dr. Rex Nash found late that afternoon, with another 150 allowed in evidence of the typical Marambaia-type alluvial the following day. On the 20th) 2,000 more miners deposit (see, e.g., Proctor, 1984)) with the gem- returned, expecting open mining to start again; a bearing gravels probably lying on top of bedrock line of parlzed cars more than a lzilometer long and under interbedded layers of sand and clay. dominated the scene. Violence ensued almost im- Unlilze the granite pebbles and boulders of Barro mediately, and the army closed the area again on Preto, 99% of the gem-bearing gravel in this area August 23. appeared to be rolled quartz pebbles in sizes of 2 to That night was one of the most violent in 10 cm (1 to 4 in.]. Dr. Nash noted that the Minas Gerais mining history. The garimpeiros set overburden - mostly clay with some sand and only fire to the eucalyptus forest opposite the mining a small amount of red soil -was 1.5 to 2 m thick. area, and even to several cars. At least one soldier Another geologist, Sabastiiio Domingos, noted was shot and approximately two dozen miners that elsewhere in the deposit the cascalho layer were wounded in the fighting that ensued (D. averaged 50 cm (20in.) thick and varied from 1 to 5 Schwartz and W Brennan, pers. comm., 1987). m below the surface. Domingos also reported a 20- Between 10 and 15 people have died at these cm-thick layer of sand-which also contained diggings so far. On August 24, the military police fragments of alexandrite-approximately 1 m rerouted one of the creelzs and flooded most of the above the main cnscalho layer. mining area so that it was virtually unworlzable. Warren Brennan noted quite different condi- On October 1, with special permission from tions in a separate region of the same narrow valley. the Minister of Mines, 60 to 70 members of the The exposed walls of several pits over 3 m deep International Gemmological Conference (IGC) showed three distinct quartz-pebble gravel layers. visited the closed mine (Koivula, 19871, but were The top layer began approximately 30-60 cm (1to allowed to stay only 45 minutes. Although the 2 ft.] deep under the surface clay layer (with very mine remains "closed" (with periodic clandestine little sand showing) and was 3045 cm thick. digging) at this writing (February 1988), it was Under that was another 3045 cm layer composed scheduled to reopen officially in March 1988 (D. mostly of clay, which overlay the middle gravel Schwartz, pers. comm., 1988). layer, 3045 cm thick. Another clay layer, over 30 cm thick, covered the bottom gravel layer almost 3 Geology and Occurrence. It is important to visual- m below the surface. Some clay was found in the ize just how small this deposit is. The mining area three predominantly quartz layers, and some is only 200 m long by 150 m wide (approximately quartz in the clay layers. The quartz layers also 650 by 500 ft.), with the diggings extending over a contained significant amounts of kaolin. Brennan roughly oval area. However, 70-80% of the choic- examined about eight piles of previously washed est rough came from a triangular-shaped area only quartz pebbles from all three layers and noted that

28 Chrysoberyl and Alexandrite of Minas Gerais GEMS & GEMOLOGY Spring 1988 represent three different periods of deposition. The top two quartz-pebble layers, lying on clay layers, are apparently colluvial deposits similar to those found at Barro Preto. The interbedded layers of clay and quartz, and the extremely high concentrations of lzaolin clay (figure 141, are seldom if ever seen in a purely alluvial environment, where the swift waters typically wash most of it away. Much of the alexandrite also showed sharp ,es or, frequently, one complete crystal face, as 11 as a number of complete crystals, some I twinned and some as large as 1.4 ci(L. ~erces- sian, A. Tavares, K. Elawar, and K. Schmetzer, pers. comm., 1987). The good crystalline condition of some of the quartz, the abundant alexandrite fragments with sharp edges and crystal faces, and the great amounts of lzaolin indicate that the cle~josit mpved less than 100 m downstream after it eroded aidweathered out of the hillside in which it had formed (R.Nash, pers. comm., 1987).Or, as at the Salinas tourmaline deposit (Proctor, 1985a), the Hemitita alexandrites actually may have I XTIoved very little but rather decomposed in place Figure 14. Great quantities of kaolin (decom. as the hillside in which they were originally posed feldspar) were foclnd at Hematita, turn- contained eroded and became part of the valley ing many of the pits almost completely white. floor (R. Nash, pers. comm., 1987). Photo by Agenor Tavares. Nash believes that several factors strongly suggest that this alexandrite deposit, unlilze the others reported in the literature (e.g., the Urals, Barras (K. Elawar and A. Tavares, pers. comm., Itabira, Carnaiba, etc.),may actually have formed 1987). in a pegmatite. Although the presence of quartz, lzaolin (from weathered feldspar), and even aqua- Mining. The first diggings in the surface dirt here marine-which are commonly associated with involved just pick and shovel work, with the soil pegmatites- could be explained by the weathering and clay being washed with screens in the nearby of pegmatites in the granite host rock at the same creeks. This method quiclzly evolved into the time as the alexandrite, the large pieces of clean excavation of square pits as deep as 5-6 m (D. alexandrite found are typical of pegmatite mineral Schwartz and S. Domingos, pers. comm., 1987; crystallization, as is the unusually large propor- again, see figures 13 and 14).After the garimpeiros tion of transparent material. Again, though, no dug their pits and extracted what gravels they alexandrite crystals have been found in situ, so could, they let the pit fill up with water and began further study is needed. the tedious washing operation with circular Statements by some dealers closely associated screens. More sophisticated garimpeiros used two with this mining operation strongly suggest that "stacked" screens, with different meshes, for better most of the best gems were found in the lower, sorting. Pumps were necessary to lzeep most of truly alluvial bedrock gravels of this valley, just as these pits workably dry (figure 15). Most of the they were at Barro Preto, Gil, Marambaia, and Tres areas mined were worked by hand.

Chrysoberyl and Alexandrite of Minas Gerais GEMS & GEMOLOGY Spring 1988 29 Production. As with most gem deposits in Minas faceted into many thousands of medium to very Gerais, production statistics are elusive, but major fine stones between 0.20 and 6 ct. One- to 2-ct dealers estimate that approximately 50 kg of stones were abundant, but 3-ct and larger stones alexandrites have been found at Hematita thus far. made up no more than 15% of the total number. Of this, however, only approximately 10 kg show Roughly 50-60% of all sizes, and especially the the best clarity and color change, resulting in very small sizes, are "clean" (K. Elawar, pers. 10,000 to 15,000 ct of fine to superior gems (L. comm., 1987), with 4045% exhibiting a good Nercessian, pers. comm., 1987). Some clean, large color change from greenish blue to some shade of pieces of 16 and 20.5 grams yielded almost exactly pink or red. Some stones that display a very 50% when cut (K. Elawar, pers. comm., 1987). attractive color change are far from clean (K. Several clean or mostly clean pieces of rough of 17 Elawar, pers. .comm., 1987). to 56 grams were also seen by H. Bank, K. Elawar, The lion's share of the production was pur- A. Tavares, and L. Nercessian, but most of the chased by four companies: K. Elawar, Ltda., Tamil rough found weighed less than 1 gram (L. Nerces- (owned by A. Tavares), and the two companies sian, pers. comm., 1987). owned by the two brothers Hilton (Zequinha) Several large faceted alexandrites - many over Lopes and Lopes Duarte. As of January 1, 1988, 10 ct and at least one as large as 30 ct -have been roughly one-third of the total production remained cut from the Hematita rough. A few superb cat's- in Te6filo Otoni. About 40% had gone to Hong eye alexandrites over 10 ct were also cut (K.Elawar, Kong and Japan, German buyers had purchased pers. comm., 1987).The bullz of the material was approximately 20% of the total, and the remainder was sold primarily to American buyers (K. Elawar and L. Nercessian, pers. comm., 1987). Although Fip~e15. Pumps were required to rid masf of much of the valley floor was dug up, it appears that the pits of waB@r at Hemcrtita. Nots also ths many sections remain untouched (D. Schwartz many circular sexaens, which the minars use to and L. Nercessian, pers. comm., 1987). However, wadi the wavels izl the& search for the narn al- - clandestine digging during 1988 has produced exadrite; Photo bj Agenor Tavars. little of value (R. Nash, pers. comm., 1988))which raises some questions as to the true potential of the deposit.

The Hematita Alexandrites. The Hematita alexandrites contain 0.30-0.44 wt.% Cr203, 1.11-1.59 wt.% Fe203, and 0.01-0.03 wt.% V203 (H. Bank and K. Schmetzer, pers. comm., 1987). The best Hematita gems compare very favorably with the best Russian material: greenish blue to blue in sunlight and pink to red in incandescent light (figure 16). Since alexandrite is trichroic, the best color can be achieved only if the cutter uses the correct orientation of the gem's table in relation to the c-axis. The best pink to red colors exhibited by this gem in incandescent light are invariably coupled with a very distinctive slightly greenish blue to blue color the Brazilians call pav60 (peacock).The best (or most complete) color change involves pavio in sunlight changing to a strong pink, raspberry, or deep "rhodolite" or "ruby" red in incandescent light. About 30% to 45% of the best 10 kg exhibited this color change (K. Elawar, pers. comm., 1987). A more greenish or yellow-green color in

GEMS & GEMOLOGY Spring 1988 Figure 16. The color change of the two Hematita alexandrites (1.06 ct -center, 1.32 ct-right) is very sdarto that of the fine Russian stone (1.29 ct) on the left. The photo at the top was taken with incandescent light; the one at the bottom with fluorescent light. The two Hematita alexandrites are courtesy of Mayer eJ Watt; the Russian alexandrite is courtesy of Mary Murphy Hammid. Photo O Tino Hammid.

sunlight is usually coupled with more purplish K. Schmetzer, and H. Hiinni, pers. comm., 1988; tones in incandescent light, while a very dark blue see Koivula and Kammerling, 1988, for photo- (with some brown or even a gray-brown) as the micrographs). predominant daylight color is usually associated with a dark brownish red or reddish purple in OTHER CHRYSOBERYL AND incandescent light (K. Elawar and A. Tavares, pers. ALEXANDRITE DEPOSITS comm., 1987). IN BRAZIL With the increased interest in alexandrites In Minas Gerais, small amounts of chrysoberyl stimulated by the Hematita discovery, there ap- have also been found near Santo Antdnio do pear to be more synthetic alexandrites on the Jacinto, located on the border with Bahia. In 1972, a market. The buyer is advised to be aware of the six-month production from Lavra dos Coimbras, distinctions between natural and synthetic alex- southwest of the AmericanaISantana valley re- andrites before he or she purchases any stone (see, gion, yielded significant amounts of al'exandrite for example, Stockton and Kane, 1988).Inclusions (H. Kennedy and A. Tavares, pers. comm., 1987).In observed in the Hematita alexandrites include August 1987, small amounts of small but clean apatite, fluorite, mica of the biotite group, and two- alexandrite were taken from another location in and three-phase inclusions (E. Giibelin, H. Bank, the Hematita region, approximately 8 km in the

Chrysoberyl and Alexandrite of Minas era is GEMS & GEMOLOGY Spring 1988 31 direction of the city of AntBnio Dias (and referred the gems found at Lavra de Hematita, which is to by that name).Other deposits are shown on the probably the single most significant alexandrite map in figure 4. deposit in history. Quite a few locations in the state of Bahia have Throughout this series of articles on gems produced chrysoberyl andlor alexandrite, includ- from the pegmatite districts of Minas Gerais, we ing Socota, Jaguda, and Jacunda (principally alex- have observed how gem rough occurs in a great andrite; H. Banlz, pers. comm., 1987) as well as variety of environments. Primary, in situ deposits Jaqueto (chrysoberyl and some alexandrite; the are not common but often produce the finest 6,250-gram 120 cm high] Mitra [or Bishop's hat] materials (see, e.g., the Jonas rubellite mine, Proc- cat's-eye was found here as was a 25.2-1zg chrys- tor, 1985b). Most primary deposits have decom- oberyl crystal).The Carnaiba emerald mine (inthe posed over time, so that the gems are found Campo Formosa area) produced some primarily dispersed in secondary deposits with either lzaolin- low-quality alexandrite and some superb sixling clay (see, e.g., the Santa Rosa and Golconda I11 crystals. Chrysoberyl or alexandrite has been tourmaline mines; Proctor, 1985b) or red soil, found near the cities of Aguas Frias, Itanhem, which represents a further degree of dispersal (see, Teixeira de Freitas, Cachoeira do Mato, Itamaraju, e.g., the Ouro Fino tourmaline mine as well as the Faria Lemos, and on the Corrego de Agua Preta (J. Pioneer and Pine Tree aquamarine mines; Proctor, Raggi and A. Lucio, pers. comm., 1987).In southern 1984, 1985a). In all of the chrysoberyl and alex- Bahia, Lag6a da Prata has produced approximately andrite deposits discussed in this article, we have 10-15 lzg of alexandrite with a light green to pink witnessed the complete dispersal of gems into color change, and consistently produces chrys- alluvial as well as colluvial gravels. oberyl and cat's-eye chrysoberyl (K. Elawar and H. Kennedy, pers. comm., 198 7). Several locations in the state of Espirito Santo also produce chrysoberyl and cat's-eye chrys- REFERENCES oberyl (but insignificant amounts of alexandrite): Ball S.H. (1930) Historical notes on genl ~nining.Econorr~ic Geology, Vol. 26, pp. 681-738. the "latina region is represented by Jo'o Bank H. (1973)From the Worldo/Gerr~stones.Umschau-Verlag, Grande and lime-green stones from Municipio de Frankfurt am Main, W. Gcrmany. Vila Panca: the Itacriso mine. 40 lzm west of Bauer M. (1904)Preciorrs Stones. Repiinted by Dover Publica- Colatina, has been one of theTlargestproducers tions, New York, 1968. Desautels EE. (1979)TPe~srlres in the Sinithsonion, the Gein Col- outside Minas Gerais (J.Raggi and L. Nercessian, lection. Smithsonian Inst~tutionPress, Washington, DC. pers. comm., 1987). Mineral collectors lznow the Interview: Allan Caplan (1980)Minertilogicnl Record, Vol. I I, No. 6, pp. 351-360. famous deposit at Itagua~u,some35 lzm southwest Koivula J. (1987)Ge~n News: More on Brazilian alexandrites. of Colatina, where a few superb cyclic sixling Gems d Gernology, Vol. W,No. 4, pp. 238&240. chrysoberyl twin crystals (called trillings) as large Koivula J., Kammerling R. 11988)Genl Ncws: Inclusions identi- as 9.5 cm were found ("Interview: Allan Caplan," fied in new Brazilian alexandrites. Gerns d Gemology, Vol. 24, No. 1, p. 56-59. 1980). Kunz C.F. (1913) Tlie Curiorls Lore of Precious Stones. Re- printed by Dover Publications, New York, 1971. CONCLUSION Pough F. ( 1973)Three fashionable minerals. Millern1 Digest, Vol. 5. DD. 25-32. For the past 50 years, the Americana and Santana ~ough'i'(1976)- Alexandrite: Gem named for a crown prince. Minernl Digest, Vol. 8, pp. 69-73. have One of the productive Proctor K. (1984) Gem pegnlatites of Minas Gerris, Brazil: regions in the world for chrysoberyl and cat's-eye Exploration, occurrence, and aquamarine deposits. Gerns chrysoberyl. The Faisca and Cilindro deposits, U) Geinology, VO~.20, NO. 3, pp. 78-100. together with B~~~~ preto and ~il are Proctor K. (1985a)Gem pegn~atitesof Minas Gerais, Brazil: The tourmalines of the Araquai districts. Geins @I Gernologj~, the largest and most consistent producers in the VO~.21, NO. 1, pp. 3-19. region. Exceptional alexandrites and cat's-eye alex- Proctor K. ( 1985b)Gem pegmatites of Minas Gerais, Brazil: The andrites have also been found in this region, at the tourmalines of the Governador Valadares district. Gei71s d Gemology, Vol. 21, No. 2, pp. 86-104. Coimbras deposit. Sinkanlzas 7. (1964) Mineralogy for Amateurs. Von Nostrand Since 1975, the Malacacheta region has devel- Co., Toronto, Canada. oped into one of the world/s alexandrite- Stockton C., Kane R. (1988)The distinction of natural from synthetic alexandrite by infrared spectroscopy. Geiris el) producing areas. In 1987, however, the production Gemology, vol. 24, NO. I, pp. 4446. at Malacacheta was eclipsed in size and quality by Webster R. (1983)Gerns, 4th ed. Butterworths, London.

32 Chrysoberyl and Alexandrite of Minas Gerais GEMS & GEMOLOGY Spring 1988